Tucson, Ariz. — The death of a border patrol agent in an nighttime gun battle Tuesday near the Arizona border has brought renewed calls for increased security from those who view the killing as a sign of growing violence along the international line.

Local officials note that deadly attacks against agents are rare in the area, with the last one happening in 1998. But the head of the border patrol agents' union acknowledges that smugglers are showing an increasing tendency to stand and fight when confronted by US law enforcement.

Border patrol agent Brian Terry died in the shootout between members of the agency’s tactical unit and several gunmen about 10 miles north of Nogales, according to Santa Cruz County Sheriff Tony Estrada. Four suspects were arrested and authorities continued to search for a fifth Wednesday.

As with the still-unsolved shooting death of Cochise Countyrancher Robert Krentz in March, Arizona politicians quickly seized upon the agent’s slaying to demand more federal action.

“The increased violence in the border region demands that Congress provide the necessary resources and personnel to ensure the safety of all Americans, especially border patrol agents stationed on the border, and fulfill the federal government’s responsibility to secure our border,” Sen. John McCain (R) said in a statement.

Added Rep. Gabrielle Giffords: “This is a tragedy that deserves nothing less than the swiftest and strongest response. It is a stark reminder that our borders are not yet secure.”

In past years, traffickers opted to drop drug loads and weapons as they tried to evade law enforcement, he says. But that seems to be changing, with several close calls for agents, particularly Arizona and Texas.

“Now what we’re seeing is more of an inclination to just to shoot it out with agents,” Mr. Bonner says of criminals.

He described the suspects involved in Tuesday’s gunfight as armed bandits who had been preying on illegal border-crossers in the area. One of the suspects was wounded in the shootout, he says.

Since 1919, 111 Border Patrol agents have died on duty in shootings, crashes, and for other reasons, according to the Officer Down Memorial Page.